package LinkedList;

// 2、无头双向链表实现
public class LinkedList {

    static class ListNode {
        public int val;
        public ListNode next;
        public ListNode prev;

        public ListNode(int val) {
            this.val = val;
        }

        public ListNode head;
        public ListNode last;

    }
    //头插法
    public void addFirst(int data) {
        ListNode node = new ListNode(data);

        if(head == null) {
            head = node;
            return;
        }

        node.next = head;
        head.prev = node;

        head = node;

    }
    //尾插法
    public void addLast(int data) {
        ListNode node = new ListNode(data);
        last.next = node;
        node.prev = last;

        last = last.next;
    }
    //任意位置插入,第一个数据节点为0号下标
    public boolean addIndex(int index,int data) {
        if(index < 0 || index > size()) {
            throw new IndexOutOfBoundsException("下标越界");
        }

        int count = index-1;
        ListNode cur = head;
        while(count !=0 ) {
            cur = cur.next;
            count--;
        }

        ListNode node = new ListNode(data);
        node.next = cur.next;
        cur.next = node;
        node.prev = cur;
        cur.next.next.prev = node;
    }
    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key){
        ListNode cur = head;
        while(cur != null) {
            if(cur.val == key) {
                return true;
            }
            cur = cur.next;
        }
        return false;
    }
    //删除第一次出现关键字为key的节点
    public void remove(int key) {
        if(head.val == key) {
            head = head.next;
        }
        if(head == null) {
            return;
        }


        ListNode cur = head;
        while(cur != null) {
            if(cur.val == key) {
                if(cur == last) {
                    cur.prev.next = cur.next;
                    last = last.prev;
                    return;
                }
                cur.prev.next = cur.next;
                cur.next.prev = cur.prev;
                return;
            }
            cur = cur.next;
        }
    }
    //删除所有值为key的节点
    public void removeAllKey(int key) {
        if(head.val == key) {
            head = head.next;
        }
        if(head == null) {
            return;
        }

        ListNode cur = head;
        while(cur != null) {
            if(cur.val == key) {
                if(cur == last) {
                    cur.prev.next = cur.next;
                    last = last.prev;
                    return;
                }
                cur.prev.next = cur.next;
                cur.next.prev = cur.prev;
            }
            cur = cur.next;
        }
    }
    //得到单链表的长度
    public int size() {
        int count = 0;
        ListNode cur = head;
        while(cur != null) {
            count++;
            cur = cur.next;
        }
        return count;
    }
    public void display(){
        ListNode cur = head;
        while(cur != null) {
            System.out.println(cur.val+" ");
            cur = cur.next;
        }
        System.out.println();
    }
    public void clear() {
        head = null;
        last = null;
    }
}